The present invention relates to an improved process for the preparation of fibers of syndiotactic vinylaromatic polymers. More particularly, the present invention relates to such a process wherein the resulting fibers possess improved physical properties, particularly increased modulus, tenacity and/or maximum strain properties.
In U.S. Pat. No. 5,006,296 a process for preparing fibers of syndiotactic polystyrene (SPS) or a mixture of SPS and isotactic polystyrene was disclosed. At col. 4, lines 18-52, fibers having drawdown ratios (measured as a ratio of fiber cross-sectional area before and after drawing) from 10:1 to 100:1 were disclosed. The fibers were further disclosed as being desirably redrawn. In the redrawing step, the fiber was elongated at a ratio between 1.5:1 and 10:1. The teachings of U.S. Pat. No. 5,006,296 is hereby incorporated by reference.
Fibers prepared by the above technique possess desirable physical properties, however in many respects they lack optimum physical properties, especially tensile modulus, tenacity and/or maximum strain properties. Accordingly it would be desirable if there were provided an improved fiber spinning process for preparing fibers of syndiotactic vinylaromatic polymers having improved physical properties.